. The main features of the northwest region of Buenos Aires Province (Argentina) are its small topographic slope, the lack of a drainage network and the presence of permeable sediments near the surface. As a consequence, there is no fluvial network and the lagoons or ponds located in the depressions are important. Landsat 5 TM images have shown good contrast between water and land areas. All available scenes between August 1998 and August 1999 were used in a multitemporal analysis. The areas of the lagoons, obtained by satellite images, in each period were compared with hydrological variables measured in situ. The results show a relationship between variations of the water balance (precipitation – evapotranspiration) and fluctuations of the water table and lagoon areas.